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.Dd June 4, 1993
.Dt RE_COMP 3
.Os
.Sh NAME
.Nm re_comp ,
.Nm re_exec
.Nd regular expression handler
.Sh LIBRARY
.Lb libcompat
.Sh SYNOPSIS
.In unistd.h
.Ft char *
.Fn re_comp "const char *s"
.Ft int
.Fn re_exec "const char *s"
.Sh DESCRIPTION
.Bf -symbolic
This interface is made obsolete by
.Xr regex 3 .
.Ef
.Pp
The
.Fn re_comp
function
compiles a string into an internal form suitable for pattern matching.
The
.Fn re_exec
function
checks the argument string against the last string passed to
.Fn re_comp .
.Pp
The
.Fn re_comp
function
returns 0 if the string
.Fa s
was compiled successfully; otherwise a string containing an
error message is returned.
If
.Fn re_comp
is passed 0 or a null string, it returns without changing the currently
compiled regular expression.
.Pp
The
.Fn re_exec
function
returns 1 if the string
.Fa s
matches the last compiled regular expression, 0 if the string
.Fa s
failed to match the last compiled regular expression, and \-1 if the compiled
regular expression was invalid (indicating an internal error).
.Pp
The strings passed to both
.Fn re_comp
and
.Fn re_exec
may have trailing or embedded newline characters;
they are terminated by
.Dv NUL Ns s .
The regular expressions recognized are described in the manual entry for
.Xr ed 1 ,
given the above difference.
.Sh DIAGNOSTICS
The
.Fn re_exec
function
returns \-1 for an internal error.
.Pp
The
.Fn re_comp
function
returns
.Dq no previous regular expression
or one of the strings generated by
.Xr regerror 3 .
.Sh SEE ALSO
.Xr ed 1 ,
.Xr egrep 1 ,
.Xr ex 1 ,
.Xr fgrep 1 ,
.Xr grep 1 ,
.Xr regex 3
.Sh HISTORY
The
.Fn re_comp
and
.Fn re_exec
functions appeared in
.Bx 4.0 .
